Making More Water Available by Using Less & Desalting the Sea Sections 5.8 & 5.9

Conservation is a must Private well owners pay to drill the well and to install the pump Public water system users usually pay based on water usage measured with a meter Studies show as rates increase, water usage decrease

Leaky Water Systems Much water is lost to leaking pipes New York City uses sonar to locate leaks in pipes or water mains It’s expensive to repair Faucet with small leak wastes 5 gpd A leaking toilet wastes 22 gpd Check for a leak: Can put food coloring in the tank…does it show up in the toilet bowl?

Water-Saving Fixtures Typical family of four consumes 255 gpd With water-saving fixtures can be reduced by 100 gpd 1992 energy bill required new plumbing fixtures to limit flow to 2.5 gpd on showerheads & faucets and 1.6 gpd on toilets Also, saves on energy (heating water)

A Change in Lifestyle During drought conditions, only serve water in restaurants if asked Use disposable dishes instead of commercial dishwashers Phoenix: asked to water lawns every three days either very early or very late Xeriscape landscaping uses native, drought tolerant plants – very popular in Phoenix

Irrigation Important for food production Improvements on wasting also reduce erosion and prevent loss of fertilizer Most efficient method is subsurface drip irrigation – buried perforated plastic pipes feeding water directly to plant roots Holes can clog and is very expensive to install Cut evaporation loss with low-energy precision application – center pivot close to ground

Use It Again Recycling water is not new As human population grows, the demand for water grows Water conservation and water recycling will be essential to ensure a sustainable water supply

Questions (don’t write this) 1. When paying for water usage, when is water wasted more often? With a flat rate or when there is a water meter 2. What technology is New York using to detect leaks? 3. How can toilet leaks be detected? 4. What are the two resources saved by saving water? 5. What are some possible changes in plumbing?

Questions (don’t write this) 1. What is xeriscaping? 2. What is the most efficient irrigation system and why don’t farmers use it? 3. Give an example of recycling water used in the past.

Desalting the Sea (5.9) Seawater is not fit to drink 3.5% salt Several methods can be used to remove salts from saline water Reverse osmosis – water forced through a membrane with openings large enough for water molecules to pass through, but too small for the salt

Electrodislysis – water flows through a container divided into three chambers, one with a positive charge, one with a negative charge, and a center chamber where water is deionized Works best with slightly salty water Otherwise would be too expensive

Flash distillation or solar distillation – both work off of the evaporation and condensation of water Technology exists, but these processes (with exception of solar distillation) require too much energy; also, very expensive Finally, where would we dispose of the brine (wastewater containing salt)?